I can guarantee that all of the following will happen in the upcoming expansion.
My dad is Blizzard so that's how you know.
-There will be a new continent you have to level through.
-There will be 5 or 10 more levels.
-The HoA is gone and replaced with a new AP grind you will hate.
-Titanforging is still in. Sockets are still random. Professions are still mostly useless.
-Warfronts are out.
-Island Expeditions are out.
-There will be a new War Campaign style thing.
-There will be new allied races at some point, each locked behind a delicious rep grind.
-There will be a new class (or not)
-It will have 4 raids total.
-It will have 7 (seven) new dungeons.
-Talents will not be overhauled, but you might get new ones.
-Abilities will not be overhauled, and you will not get new ones. You might get old ones back.
-Classes will be reworked. Shamans will still suck.
Now for details on the story!
-It will be poorly written
-It will feature characters that you don't like.
-Sylvanas, Vol'jin, Tyrande, and a surprise person (we retconned back to life) will be major characters.
-There's an overarching villain. We make it seem like he's a big deal, but he goes down like a chump. Like every single big bad since Arthas.
-Dragons will be involved to some degree.
-Titan stuff will be involved to some degree.
-All the characters who were major players in BFA (Talanji, Jaina, etc) are tossed in the trash and play no further role going forward.
-Magni will still give world quests
-Khadgar might come back.
-Lor'themar and Thalryssa hook up. Foreshadowing for a new system where you play wingman for NPCs (Champion! Fetch me some condoms!).
I can't leak anything else right now guys, J Allen is standing behind my desk and I'm pretty sure I'm about to get a promotion.